The Ethiopian authorities have reopened the University of Addis Ababa after last week's disturbances in which 39 people were killed and 250 injured.

Never in the history of Ethiopia have we seen this gangsterism.

Ethiopian official Yemane Kidane

The worst unrest in Addis Ababa for several years broke out when students defied a government ultimatum to end a protest against the presence of policemen on campus.

The students now have two days in which to re-register for their courses, but although the gates of the Addis Ababa campus are open, the students have been slow to come back.

Students are adamant that they will not return to classes until the police have released thousands of their colleagues who have been detained in police stations and detention camps.

A senior Ethiopian official, Yemane Kidane, dismissed accusations by opposition activists that the unrest signaled popular discontent with the government.

Gangsterism

He told Reuters news agency that jobless youths and gangsters had taken advantage of the student demonstrations to launch an orgy of theft and destruction and he said there would now be a crackdown on criminal gangs in the capital.

The government is blaming gangsters for the worst violence for years

"Never in the history of Ethiopia have we seen this gangsterism. Student protests have always been peaceful," he said.

"There is big unemployment in Addis that perpetuates that kind of gangsterism. It's fertile ground for criminals."

Mr Yemane, who is chief of staff at the foreign ministry, also defended the police shootings of protestors saying they had the right to defend the security of people and their property.

Human rights groups accused the police of using excessive force to curb the protests.

Detention

Thousands of students and young people were rounded up by police after the riots last week and are being held just outside the capital.

Authorities say the detainees are not being mistreated

Hundreds of worried parents went to the police training centre at Sendafa from all over the country looking for their children.

Mr Yemane said he expected students and anyone with no case to answer to be released in stages.

"They will be released step by step, selectively, the students earlier than anyone else," he said.

"Suspected criminals would be taken to court, and the guilty would be sentenced and taught a lesson," he said.